[JackieTien97]

Description

Fix two partition-boundary defects in pattern_match:

• Partition processors shared one QetchAlgorithm. With two partitions of five rows each, the second emitted pass-through indexes 5..9 against a five-row cache and failed with Invalid position 5 and length 1 in block with 5 positions.
• A singleton partition had no curve section, but finalization dereferenced that missing section and threw NullPointerException.

Create and configure a fresh algorithm for each processor. Finish inputs that have not formed a section without producing matches. Ordinary and regex regression tests cover successive partitions, independently interleaved processors, and singleton partitions before, between, and after matching partitions.

Validation

• The three isolation regressions fail before the isolation fix. Both new singleton regressions reproduce the null-pointer failure before the boundary fix.
• Clean reactor verification with TableSimpleIT: all 5 unit tests and both SQL integration tests passed in a 1 ConfigNode / 1 DataNode environment.
• Clean reactor test of node-commons and its dependencies with with-zh-locale: all 5 unit tests passed.
• Spotless, Checkstyle, and license checks passed in the isolated verification checkout.

mvn clean verify -pl integration-test -am -P with-integration-tests,TableSimpleIT \
  -Dtest=PatternMatchTableFunctionTest \
  '-Dit.test=IoTDBWindowTVFIT#testPatternMatchPartitions+testPatternMatchRegexPartitions' \
  -DfailIfNoTests=false -Dsurefire.failIfNoSpecifiedTests=false \
  -Dfailsafe.failIfNoSpecifiedTests=false

mvn clean test -pl iotdb-core/node-commons -am -P with-zh-locale \
  -Dtest=PatternMatchTableFunctionTest \
  -Dsurefire.failIfNoSpecifiedTests=false -DfailIfNoTests=false

This PR has:

• been self-reviewed.
• added comments explaining the intent of the changes.
• added unit tests.
• added integration tests.
• been tested in a test IoTDB cluster.

[JackieTien97]

Please address the singleton-partition failure described inline and add regression coverage. This is a pre-existing defect reproduced with both the base and PR implementations; the current partition-state isolation tests pass clean verification.

[JackieTien97]

Handle singleton partitions without throwing. The partition fixtures here all contain at least four rows, so they miss a real boundary failure: processPartition(createProvider(pattern).getDataProcessor(), new double[] {1}) throws a NullPointerException for both "1,2,3,2,1" and "1,{2,3,2}+,1", using the parameters already configured by createProvider().

addPoint() creates nowSection only after the second point, but finish() unconditionally calls closeNowDataSegment() → closeNowSection(), which dereferences it at QetchAlgorithm.java:469. A one-row partition should finish with no matches. Please handle this boundary and add separate ordinary/regex regression tests, including singleton partitions before or after a matching partition.

I reproduced this with both the base implementation (2abe6e925e) and the PR implementation (d1728308b7); this is a pre-existing defect, not a regression introduced by this PR.